Active IP Forwarding in an Event Driven Virtual Link Aggregation (vlag) System

1. A networking switch, comprising: an interswitch link (ISL) interface configured to couple the networking switch with a second networking switch via an ISL; at least one networking port configured to connect to an access switch in Layer-2 (L2) via a virtual link aggregation (vLAG) comprising connections with the second networking switch; and a virtual router redundancy protocol (VRRP) module configured to: interact and modify a VRRP state machine to perform active internet protocol (IP) forwarding when a connection fails between the second networking switch and the access switch or the second networking switch does not function properly; and indicate state events associated with the vLAG to the second networking switch via the ISL, wherein the state events comprise: a state indicating initialization when neither networking switch connected via the ISL is currently active (INITIAL), a state indicating that the vLAG is active on the networking switch only (LOCAL-UP), a state indicating that the vLAG is active on the second networking switch only (REMOTE-UP), and a state indicating that the vLAG is active on both networking switches (FORMED), wherein the networking switch is positioned at a boundary between L2 and Layer-3 (L3), and wherein the second networking switch is positioned at the boundary between L2 and L3.

2. The networking switch as recited in claim 1 , wherein the VRRP module is configured to indicate a status of the networking switch to the second networking switch via the ISL, wherein the status comprises: an initialization status when the networking switch is not currently active (INIT), a back-up status when the networking switch is acting as a back-up switch (BACK-UP), and a master status when the networking switch is acting as a master switch (MASTER).

3. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the INITIAL state to the LOCAL-UP state and detection of a virtual router instance over the vLAG having the BACK-UP status, set up active IP forwarding on the networking switch such that address resolution protocol (ARP) requests are responded to by the networking switch.

4. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the LOCAL-UP state to the FORMED state, synchronize address resolution protocol (ARP) entries with a vLAG peer switch that have been learnt over the vLAG.

5. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the REMOTE-UP state to the FORMED state and detection of a virtual router instance over the vLAG having the BACK-UP status, set up active IP forwarding on the networking switch such that address resolution protocol (ARP) requests are responded to by the networking switch.

6. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the LOCAL-UP state or the FORMED state to the INITIAL state and detection of a virtual router instance over the vLAG having the BACK-UP status, reset settings for performing active IP forwarding.

7. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the BACK-UP status to the INIT status and detection of the second networking switch indicating the LOCAL-UP state or the FORMED state, reset settings for performing active IP forwarding.

8. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the INIT status to the BACK-UP status and detection of the second networking switch indicating the LOCAL-UP state or the FORMED state, set up active IP forwarding on the networking switch such that address resolution protocol (ARP) requests are responded to by the networking switch.

9. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the INIT status to the BACK-UP status and detection of the second networking switch indicating the LOCAL-UP state or the FORMED state, set up active IP forwarding on the networking switch such that address resolution protocol (ARP) requests are responded to by the networking switch and send a request to synchronize all ARP entries learnt over the vLAG with a vLAG peer switch.

10. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the MASTER status to the BACK-UP status and detection of the second networking switch indicating the LOCAL-UP state or the FORMED state, preserve programmed active IP forwarding settings.

11. The networking switch as recited in claim 2 , wherein the VRRP module is configured to, in response to detection of a transition from the BACK-UP status to the MASTER status and detection of the second networking switch indicating the LOCAL-UP state or the FORMED state, preserve programmed active IP forwarding settings.

12. A method comprising: coupling a first networking switch with a second networking switch using an interswitch link (ISL), wherein the first networking switch is positioned at a boundary between Layer-2 (L2) and Layer-3 (L3), and wherein the second networking switch is positioned at the boundary between L2 and L3; creating a virtual link aggregation (vLAG) comprising connections between the first and second networking switches and an access switch in L2, wherein each networking switch comprises a virtual router redundancy protocol (VRRP) module; interacting and modifying a VRRP state machine to perform active internet protocol (IP) forwarding when a connection between one of the networking switches and the access switch fails or one of the networking switches does not function properly; and indicating state events using each of the first and second networking switches associated with the vLAG via the ISL, wherein the state events comprise: a state indicating initialization when neither switch connected via the ISL is currently active (INITIAL), a state indicating that the vLAG is active only on a local networking switch (LOCAL-UP), a state indicating that the vLAG is active only on a remote networking switch (REMOTE-UP), and a state indicating that the vLAG is active on both networking switches connected via the ISL (FORMED).

13. The method as recited in claim 12 , further comprising indicating status using each of the first and second VRRP modules of their respective switch associated with VRRP via the ISL, wherein the status comprises: an initialization status when a networking switch is not currently active (INIT), a back-up status when a networking switch is acting as a back-up switch (BACK-UP), and a master status when a networking switch is acting as a master switch (MASTER).

14. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, setting up active IP forwarding such that address resolution protocol (ARP) requests are responded to in response to detection of a transition from the INITIAL state to the LOCAL-UP state and detection of a virtual router instance over the vLAG having the BACK-UP status.

15. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, synchronizing address resolution protocol (ARP) entries with a vLAG peer switch that have been learnt over the vLAG in response to detection of: a transition from the LOCAL-UP state to the FORMED state; or a transition from the INIT status to the BACK-UP status and detection of a networking switch in the vLAG indicating the LOCAL-UP state or the FORMED state.

16. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, setting up active IP forwarding such that address resolution protocol (ARP) requests are responded to in response to detection of a transition from the REMOTE-UP state to the FORMED state and detection of a virtual router instance over the vLAG having the BACK-UP status.

17. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, resetting settings for performing active IP forwarding in response to detection of: a transition from the LOCAL-UP state or the FORMED state to the INITIAL state and detection of a virtual router instance over the vLAG having the BACK-UP status; or a transition from the BACK-UP status to the INIT status and detection of virtual router instance over the vLAG having the LOCAL-UP state or the FORMED state.

18. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, requesting to synchronize all ARP entries learnt over the vLAG with a vLAG peer switch and setting up active IP forwarding such that address resolution protocol (ARP) requests are responded to in response to detection of a transition from the INIT status to the BACK-UP status and detection of a networking switch in the vLAG indicating the LOCAL-UP state or the FORMED state.

19. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, preserving any programmed active IP forwarding settings in response to detection of a transition from the MASTER status to the BACK-UP status and detection of a networking switch in the vLAG indicating the LOCAL-UP state or the FORMED state.

20. The method as recited in claim 13 , further comprising, using each of the first and second networking switches, preserving programmed active IP forwarding settings in response to detection of a transition from the BACK-UP status to the MASTER status and detection of a networking switch in the vLAG indicating the LOCAL-UP state or the FORMED state.